Inbreeding and family index selection for prolificacy in pigs

1988 ◽  
Vol 46 (1) ◽  
pp. 79-85 ◽  
Author(s):  
M. A. Toro ◽  
L. Silio ◽  
J. Rodrigañez ◽  
M. Teresa Dobao
Keyword(s):  
Genetic Model ◽  
Finite Size ◽  
Reproductive Traits ◽  
Selection Response ◽  
Selection Method ◽  
Inbreeding Coefficient ◽  
Family Selection ◽  
The Family ◽  
Selection Indices ◽  
Selection For

ABSTRACTThe use of family selection indices has been proposed as a promising selection method for increasing prolificacy in pigs. Responses of up to 0-50 pigs per litter per generation are predicted from selection programmes using information from the dam and from relatives (full and half-sibs) of the dam and sire. In order to test this method in populations of finite size, the rates of selection response and the accumulation of inbreeding have been studied by simulation along 10 generations in a selected herd of 10 sires and 100 dams using five different family selection indices (Id, Ifd, Ihd, Ifs, Ihs). Two undesirable features were evident: (a) the standard deviations of indices were lower than those expected; and (b) the increase of inbreeding was up to three times that expected without selection. Both effects increased with the complexity of the family index reducing the rates of selection responses per generation, when a genetic model with dominance was assumed, to values close to 0·20 piglets, similar to those obtained with the basic index (Id). Some results of inbreeding effects on reproductive traits in three strains of an old closed herd of Iberian pigs are also presented. Multiple regression analysis of data from 4657 litters indicated a decrease in the number of live born ranging from 0·14 to 0·35 piglets per 10% increase in dam or litter inbreeding coefficient.

scholarly journals THEORETICAL MODIFICATIONS OF RECIPROCAL RECURRENT SELECTION

Genetics ◽  
1976 ◽  
Vol 84 (1) ◽  
pp. 95-111
Author(s):  
J Moreno-Gonzalez ◽  
M Grossman
Keyword(s):  
Recurrent Selection ◽  
Genetic Model ◽  
Selection Method ◽  
Reciprocal Recurrent Selection ◽  
Family Selection ◽  
Gene Frequencies ◽  
Complete Dominance ◽  
Selection Systems ◽  
Different Populations ◽  
Selection For

ABSTRACT Reciprocal recurrent selection (RRS), which assumes overdominant loci to be important, alters two genetically different populations to improve their crossbred mean. Individual plants from two populations (A and B) are selfed and also crossed with plants from the reciprocal female tester population (B and A, respectively). Selection is based on the mean of crossbred families, and the selected individuals are randomly mated within A and B to form new populations.—We propose two alternatives to RRS. The first (RRS-I) uses, as the tester of population A, a population (LB) that is derived from population B by family selection for low yield. The second (RRS-II) is similar to RRS-I, but also uses, as the tester of B, a population (LA) that is derived from population A by family selection for low yield.—The expected crossbred means of RRS, RRS-I, and RRS-II were compared, assuming equal σP, at several cycles of selection for incomplete and complete dominance, and for several cases of overdominance (depending on the gene frequencies in A and B, and on the equilibrium gene frequency).—The choice of selection method depends on the importance of the effects of overdominant loci compared to loci exhibiting incomplete or complete dominance. If overdominance is unimportant, RRS-II is the best selection method, followed by RRS-I and RRS. If overdominance is important, both RRS and RRS-I are superior to RRS-II; RRS is preferred to RRS-I if the effects of overdominant loci are sufficiently important. If the genetic model is a mixture of levels of dominance at different loci, a combination of selection systems is suggested.

scholarly journals EFFECTS OF POPULATION SIZE AND SELECTION INTENSITY ON SHORT-TERM RESPONSE TO SELECTION FOR POSTWEANING GAIN IN MICE

Genetics ◽  
1973 ◽  
Vol 73 (3) ◽  
pp. 513-530
Author(s):  
J P Hanrahan ◽  
E J Eisen ◽  
J E Legates
Keyword(s):  
Population Size ◽  
Selection Response ◽  
Selection Intensity ◽  
Realized Heritability ◽  
Family Selection ◽  
Effective Population ◽  
Population Sizes ◽  
Selection For ◽  
Selection Intensities ◽  
Term Response

ABSTRACT The effects of population size and selection intensity on the mean response was examined after 14 generations of within full-sib family selection for postweaning gain in mice. Population sizes of 1, 2, 4, 8 and 16 pair matings were each evaluated at selection intensities of 100% (control), 50% and 25% in a replicated experiment. Selection response per generation increased as selection intensity increased. Selection response and realized heritability tended to increase with increasing population size. Replicate variability in realized heritability was large at population sizes of 1, 2 and 4 pairs. Genetic drift was implicated as the primary factor causing the reduced response and lowered repeatability at the smaller population sizes. Lines with intended effective population sizes of 62 yielded larger selection responses per unit selection differential than lines with effective population sizes of 30 or less.

scholarly journals Selection for the length of the spermatozoan midpiece in the mouse

1970 ◽  
Vol 16 (3) ◽  
pp. 261-275 ◽  
Author(s):  
D. M. Woolley
Keyword(s):  
Electron Microscope Study ◽  
Selection Response ◽  
Sperm Cells ◽  
Realized Heritability ◽  
Family Selection ◽  
Selected Lines ◽  
Selection Programme ◽  
Proportionate Change ◽  
The Subject ◽  
Selection For

SUMMARYA subcellular dimension, the length of the spermatozoan midpiece, has been the subject of a two-way selection programme in mice. After thirteen generations of within-family selection the divergence between the selected lines amounted to 5·4 phenotypic standard deviations. The realized heritability was found to be 0·76 ± 0·02, dominance and commonenvironmental effects being apparently very small. The reality of the selection response was verified in measurements on live spermatozoa. Other measurements have shown that the change in the length of the midpiece has been independent of its width, and has occurred without a proportionate change in the length of the main-piece of the flagellum. An electron microscope study has shown that the selection has, in fact, brought about changes in the quantity of mitochondrial material in the sperm cells.

scholarly journals 215 Selection response for meat quality and carcass composition in commercial pigs using crossbred and purebred traits as predictors

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 45-45
Author(s):  
Emmanuel A Lozada-Soto ◽  
Justin Fix ◽  
Clint Schwab ◽  
Francesco Tiezzi
Keyword(s):  
Meat Quality ◽  
Lower Cost ◽  
Economic Value ◽  
Cost Effective ◽  
Selection Response ◽  
Carcass Composition ◽  
Direct Selection ◽  
Selection Indices ◽  
Breeding Objectives ◽  
Selection For

Abstract Meat quality (MQ) and carcass composition (CC) are traits with high economic value, but their phenotyping costs makes direct selection for these traits economically unsustainable. Evaluation of traits with lower cost of collection in crossbred (CB) and purebred (PB) animals for use in selection for MQ and CC remains limited. The aim of this study was to measure the response to selection of economically important MQ and CC traits using different selection indices built on cost-effective correlated traits. Phenotypic and genomic information (using 60K SNP chips) was collected for three-way CB (n = 1227 to 5117 phenotyped, n = 1252 genotyped) and PB (n = 3,251 phenotyped, n = 1035 genotyped) Duroc animals belonging to 28 paternal half-sib families. The three breeding objectives (for which response was estimated) were intramuscular fat (IMF), slice shear force (SSF), and loin weight (LW). In total 7 different selection indices (A-G) were used to estimate the selection response for each breeding objective (Table 1). Heritability and genetic correlation parameters for all traits were estimated using GIBBS1F90. Selection response was obtained as expected response per generation weighed by the accuracy of breeding values estimated from a 4-fold cross validation, where animals were grouped based on sire relatedness. For all three breeding objectives, the index which provided best selection response was A (direct selection), with values of 0.35%, -0.72 kg, and 0.85 kg for IMF, SSF, and LW respectively. The index which provided the second-best selection response was B (color and pH traits) for all three breeding objectives, with values of 0.15%, -0.26kg, and 0.30kg for IMF, SSF, and LW respectively. Results for selection response using indices C-G can be found in Table 1. In the absence of direct selection due to high costs of phenotyping, respectable selection response can be achieved by indirect selection using traits with lower cost of collection.

scholarly journals Two-way within-family and mass selection for 8-week body weight in different mouse populations

1984 ◽  
Vol 43 (2) ◽  
pp. 191-200 ◽  
Author(s):  
Ines von Butler ◽  
Henning Willeke ◽  
Franz Pirchner
Keyword(s):  
Body Weight ◽  
Inbred Strains ◽  
Selection Response ◽  
Mass Selection ◽  
Individual Selection ◽  
Family Selection ◽  
Body Weights ◽  
Selection For ◽  
Size At Birth ◽  
Better Than

SUMMARYTwo mouse populations, randombred albino mice and a cross of four inbred strains, were divergently selected for high (H8) and low (L8) 8-week body weight over 18 generations using within-family and individual selection. The crossbreds showed asymmetry of selection response and realized heritabilities (H8 0·29 ± 0·01; L8 0·17 ± 0·01). In the randombred population realized heritabilities were symmetrical (H8 0·23 ± 0·01; L8 0·22 ± 0·02). Over the first nine generations individual selection was nearly 40 per cent better than within-family selection, as was expected from the full sib correlation in both populations. As selection progressed, within-family selection reached 82% and 61% of the responses obtained with individual selection in the crossbreds and randombred respectively. Correlated responses for 3-week (weaning) and 5-week body weights agreed with observations made on direct responses, but selection for L8 did not reduce weaning weight. Selection for L8 decreased and selection for H8 increased first litter size at birth. However, mass-selected L8-pairs had a higher life-reproduction and life-span than H8-pairs.

Estimation of Genetic Parameters and Selection Response for Reproductive and Growth Traits in Rideau-Arcott sheep

2020 ◽  
Author(s):  
Mohammed Naser Boareki ◽  
Luiz Brito ◽  
Angela Cánovas ◽  
V.R. Osborne ◽  
Flavio S Schenkel
Keyword(s):  
Litter Size ◽  
Genetic Parameters ◽  
Growth Traits ◽  
Reproductive Traits ◽  
Selection Response ◽  
Direct Selection ◽  
Correlated Response ◽  
Response To Selection ◽  
Weaning Weight ◽  
Selection For

The goal of this study was to estimate genetic parameters and predict direct and correlated response to selection for lamb growth traits and ewe reproductive traits, based on single trait selection or combining multiple traits in an optimum index that targets total litter post-weaning weight in the first lambing as the main selection goal. Heritability estimates ranged from 0.04 to 0.19. Genetic correlations between growth and reproductive traits ranged from -0.24 to 0.15. The indirect response to selection for reproductive traits in later lambings, by selecting on first lambing performance, was 11 to 25% greater than direct selection. The response to indirect selection for composite reproductive traits, i.e. total weaning weight or total post-weaning weight, by selecting on individual lamb weaning weight or post-weaning weight was 1 to 69% greater than direct selection, but it was accompanied by a negative response on litter size. However, combining alternate growth and reproductive traits in optimum selection index resulted in correlated response of up to 96% greater than direct selection response for reproductive traits without a negative response on litter size. Therefore, multiple trait selection using an index of component traits was more effective than direct selection for a composite trait.

scholarly journals The number of loci affecting a quantitative trait in Drosophila melanogaster revealed by artificial selection

1983 ◽  
Vol 42 (2) ◽  
pp. 137-149 ◽  
Author(s):  
Araceli Gallego ◽  
Carlos López-Fanjul
Keyword(s):  
Initial Response ◽  
Selection Method ◽  
Base Population ◽  
Response To Selection ◽  
Family Selection ◽  
Selected Lines ◽  
Additive Variance ◽  
Bristle Number ◽  
Selection Limit ◽  
Selection For

SUMMARYIndividual and within-full-sib family selection for low sternopleural bristle number was carried out for 17 generations, with six replicate lines for each selection method. Our results can be summarized as follows: (1) the response to selection was exhausted very quickly, (2) the additive variance of the selected lines declined rapidly, (3) the variation in response to selection decreased as selection progressed, (4) genetic differences among replicates at the selection limit were small, (5) individual selection resulted in a higher initial response than within-family selection, but similar limits were achieved with both procedures. These observations are consistent with the hypothesis that the pattern of response to selection is due to the segregation in the base population of only a few loci with large effects, at intermediate frequencies.

scholarly journals ESTIMASI HERITABILITAS DAN RESPONS SELEKSI PERSILANGAN IKAN GURAMI (Osphronemus goramy Lac.)

2016 ◽  
Vol 11 (1) ◽  
pp. 23
Author(s):  
Sularto Sularto ◽  
Rita Febrianti ◽  
Suharyanto Suharyanto
Keyword(s):  
Body Weight ◽  
Standard Error ◽  
Selection Response ◽  
The Body ◽  
Selection Differential ◽  
Base Population ◽  
Family Selection ◽  
The Family ◽  
High Level ◽  
Estimated Heritability

Ikan gurami (Osphronemus goramy Lac.) dikenal sebagai ikan yang lambat tumbuh. Perbaikan mutu genetik dapat dilakukan untuk mengatasi kendala tersebut, salah satunya adalah melalui program seleksi. Pembentukan populasi dasar dengan menggabungkan persilangan empat populasi Kalimantan, Jambi, Majalengka (M), dan Tasikmalaya dilakukan untuk meningkatkan keragaman genetik. Tujuan penelitian ini untuk mengestimasi nilai heritabilitas dan respons seleksi karakter pertumbuhan bobot ikan gurami hasil persilangan empat populasi gurami sebagai populasi dasar. Persilangan dilakukan dengan rasio jantan: betina (1:1) dan terbentuk 12 famili. Seleksi dilakukan menggunakan metode seleksi famili berdasarkan karakter bobot. Parameter yang diamati adalah karakter pertumbuhan bobot. Data yang digunakan untuk perhitungan etimasi heritabilitas dan respons seleksi adalah data bobot pada umur 11 bulan. Dari data tersebut digunakan untuk menghitung koefisien keragaman (CV), diferensial seleksi (S), estimasi nilai heritabilitas (h2), estimasi respons seleksi (R), dan standard error (SE). Hasil penelitian menunjukkan bahwa populasi dasar yang terbentuk memiliki nilai estimasi heritabilitas 0,4991 yang termasuk kategori tinggi, diferensial seleksi sebesar 124,22 g; sehingga mendapatkan nilai estimasi respons seleksi sebesar 62 g atau (18,2%).Giant gourami (Osphronemus goramy Lac.) is known as a slow growing fish. Genetic improvement can be done to overcome this obstacle; one way is through the selection program. Formation of base population by combining cross four populations can increase genetic diversity. The crosses four populations were: Kalimantan (Borneo), Jambi, Majalengka, and Tasikmalaya. The purpose of this study was to estimate the heritability and response to selection of characters in length and weights of giant gourami from four crosses population as the base population of synthetic material. Crossings were made with the ratio of male: female (1:1) to form 12 families. Selection was made after 11 months old fish. Selection was done using the family selection method based on the body weight character. Observations were conducted on parameter the body weight (BW). The data was used to calculate the coefficient of variance (CV), the selection differential (S), the estimated heritability (h2), the estimated selection response (R), and standard error (SE). The result showed an estimated heritability value was 0.4991 and categorized as high level, amounting to 124.22 g of selection differential, so the estimated selection response value was 62 g (18.2%).

COMPARISON OF FOUR METHODS OF SELECTION FOR RESISTANCE TO LEPTOSPHAERULINA BRIOSIANA IN ALFALFA

1979 ◽  
Vol 21 (2) ◽  
pp. 179-186 ◽  
Author(s):  
R. R. Hill Jr. ◽  
K. T. Leath
Keyword(s):  
Selection Method ◽  
The Other ◽  
Correlated Response ◽  
Response To Selection ◽  
Selection Methods ◽  
Family Selection ◽  
Colletotrichum Trifolii ◽  
Family Types ◽  
Medicago Sativa L ◽  
Selection For

Three cycles of selection for resistance to Leptosphaerulina briosiana (Poll.) Graham &Luttrell were conducted in two alfalfa (Medicago sativa, L.) germplasm pools, MSA and MSB. Each germplasm pool was used to compare four methods of selection: phenotypic recurrent, half-sib family, full-sib family, and alternating generations of selfed family and half-sib family. Response to selection for resistance to L. briosiana was greater in MSA than in MSB. Differences between selection methods were not significant. Selection for resistance to L. briosiana generally increased resistance to Stemphylium botryosum Wallr., but the magnitude of the correlated response varied with germplasm pool and selection method. The initial selfed families in both germplasm pools were significantly less resistant to Colletotrichum trifolii Bain than the other family types. Resistance to C. trifolii increased with selfed family selection for resistance to L. briosiana in MSA but not in MSB.

scholarly journals The Prediction of Selection Response in A Self-Fertilizing Species II. Family Selection

1969 ◽  
Vol 22 (5) ◽  
pp. 1245 ◽  
Author(s):  
DG Pederson
Keyword(s):  
Genetic Model ◽  
Selection Response ◽  
Single Locus ◽  
Complex Method ◽  
Family Selection ◽  
Locus Model ◽  
Unselected Population ◽  
Combined Selection ◽  
Change In Mean ◽  
Selection Of

The response to between-and within-family selection is considered for self-fertilizing populations. For a general genetic model involving m alleles at each of k loci the expected responses are written as the sum of (1) the natural change in mean due to decreasing heterozygosity, and (2) a component which is a function of the genetic and environmental variances within an unselected population. A single-locus model is then considered and the expected responses are written in terms of para-meters of the base population. General expressions are given for the ultimate response following relaxation of selection and these are interpreted in terms of the single-locus model. In the final section the efficiencies of the various methods are investigated. In general, within-family selection is relatively inefficient while between-family selection is usually to be preferred over the selection of individuals or the more complex method of combined selection.

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